Source : Webster's Revised Unabridged Dictionary (1913)

Barbule \Bar"bule\, n. [L. barbula, fr. barba beard.]
   1. A very minute barb or beard. --Booth.

   2. (Zo["o]l.) One of the processes along the edges of the
      barbs of a feather, by which adjacent barbs interlock. See
      {Feather}.